The Pole, one of the most promising drivers of his generation, was very nearly killed in a rally crash in Italy in early 2011.

Having narrowly avoided amputation of the right hand, the 28-year-old underwent multiple operations to attend to fractures of the arm and leg. But he is now back racing, albeit with limited mobility in his right arm due to nerve damage.

Kubica's reputation and promise is such that Mercedes-Benz have handed him a trial in a DTM German touring car in Valencia on Thursday, prompting speculation that he could one day return to single-seaters.

The Pole cautioned that day was still some way off, with the cramped confines of a monocoque chassis still an issue for him, but said he was not giving up hope.

"I still believe I can come back," Kubica told F1 Racing magazine. "It's not just a dream. Right now I have limitations driving single-seaters but they are less than they look from the outside.

"Day by day, rally by rally and test by test I see fewer limitations and my goal is one day to drive properly. I don't think pace will be a problem.

"When I drive it takes concentration and I forget my body's limitations. With the damage I have, I cannot (ever) achieve 100 per cent of what I had before - but I hope to improve.

"If the limited pronation and supination were fixed 80 per cent, I would say 'yes' to coming back to F1.”

Toto Wolff, the new head of motorsport for Mercedes, admitted he would “love” to see Kubica back in a Formula One car in the future, but conceded that this week’s test was a step into the unknown.

"We all obviously like Robert,” Wolff said. “He's very special. I think what we want to do at Mercedes-Benz is give him a chance of doing a proper test in a proper racing car, seeing how he goes and how he feels.

"He's not 100 per cent fit yet. It's the first time he's in a car with downforce and I think we have to take it from there.

"If we see that he is doing well in a proper racing car with downforce, I think there are still some physical constraints to driving a monocoque chassis, with his elbow and with his arm.”